1. Field of the Invention
The present invention relates to an ionization device, a mass spectrometer including the ionization device, an image display system including the mass spectrometer, and an analysis method.
2. Description of the Related Art
There are technologies to ionize solid materials in an atmospheric pressure environment for a component analysis of a sample.
Also, an imaging mass spectrometry (IMS) has been developed, which displays an image indicating what kind of substance exists on which part of the surface.
U.S. Pat. No. 8,097,845 discloses a method of providing a solvent to a fine region of a solid surface in an atmospheric pressure environment to ionize a substance (solute) dissolved in the solvent.
The specification of U.S. Pat. No. 8,097,845 discloses use of a supply capillary and a collection capillary. The two capillaries are positioned such that mutual end portions are situated at very close positions. One capillary (supply capillary) supplies a solvent, and the other capillary (collection capillary) moves a solvent (solution) containing a solute from the solid into an ionization portion. A high voltage is applied to the solvent, and the solute is ionized in the ionization portion at the end portion of the above-described other capillary.
Further, a method of irradiating a liquid sample mixed with an analyte with laser light to improve ionization efficiency of the analyte has been proposed in Japanese Patent No. 4366508.
In the method of Japanese Patent No. 4366508, it is known that the ionization can be facilitated by using local heating due to absorption of infrared laser light by water molecules in the solvent.
However, in the method disclosed in U.S. Pat. No. 8,097,845, locations of a process of dissolving a sample in a solvent (sampling process) and of a process of occurrence of ionization (ionization process) are separated, and a time lag exits between the processes. Therefore, it is difficult to perform the analysis at high speed.
In addition, the sampling process occurs in a space and the ionization process occurs in a different space. After the sampling process, the solvent are continuously transported to the ionization process through the passage. As the sample surface is scanned with the capillary in order to image the distribution of components on the solid surface, the solvent, in which the sample is dissolved, may be mixed while passing through the passage, and it may be difficult to correspond the position of the sampling process and the obtained result of the ionization.
In addition, in the method disclosed in Japanese Patent No. 4366508, it is necessary that the sample is dissolved in the solvent in advance, and it is difficult to dissolve the fine region of the sample and to promptly perform the ionization.